SA man had dark web site to sell fentanyl

A South Australian man who started a website called Friends of Fentanyl to buy and sell the drug was motivated by his own addiction, a court has heard.

Douglas William Barrett, 33, co-owned the kiosk at Port Vincent with his wife, Alexandria Chappell, when he was arrested in December 2016.

He suffered chronic back pain and developed a "serious dependence and addiction" to fentanyl, a synthetic opioid up to 100 times stronger than morphine that can be deadly if overdosed, the District Court heard on Monday.

Grant Algie SC, for Barrett, said by August 2016 his client was spending $5000-$6000 each month "topping up" his prescription medication with the drug.

"He then became aware that he could get more for less money if he bought it in a larger quantity, discount for bulk you might say," he said.

The court heard Barrett set up the Friends of Fentanyl website on the dark web and made 31 sales within the following five weeks, resulting in a return of $4740.

Mr Algie said a consignment intercepted by police in late October 2016 included three grams of pure fentanyl.